"To address the shortfall in security workforce due to the isolation, 900 military personnel have been deployed to take over the work of the civil safety personnel," the organizing committee said in a statement. "They will work across 20 venues until all affected workforce are able to return to duty."

Lee Hee-beom, chairman of the PyeongChang Olympics organizing committee, said Tuesday that they'll be sequestered until they're declared well.

He said results of tests on the workers will come out soon.

Officials are examining food and water sources at a mountainside facility in PyeongChang, where the guards had been staying, and also inspecting 18 other facilities that rely on groundwater.

"Surveys on tap water, the food preparation staff and food items are currently being conducted to trace the route of transmission," organizers said.

Norovirus is a contagious virus that causes stomach pain, nausea and diarrhea. The most effective way to stop the spread is to practice good hand-washing and personal hygiene.